Fix responsive layout for "My assignments"

Fixes #18

app/views/assignments/by_user.html.erb

-<div>
+<div class="max-w-full">
   <h1 class="text-xl my-4 dark:text-red-500">
     Assignments for
     <%= link_to @user.name, user_assignments_path(@user) %>
@@ -23,9 +23,9 @@
     <% end %>
   </div>
 
-  <div>
-    <h2 class="text-lg my-4">Table View</h2>
-    <table class="border *:border">
+  <div class="overflow-x-auto max-w-full">
+    <h2 class="text-lg my-4 sticky left-0">Table View</h2>
+    <table class="border *:border w-full">
       <thead>
         <tr class="*:font-bold *:border">
           <th>Date</th>